Process for the production of trans-1,2-dihalogenoethylenes

摘要

Trans-1,2-dihalogenoethylenes which may be substituted are prepared by passing acetylene or another aliphatic hydrocarbon having at least one triple bond, at a temperature between 60 and 120 DEG C. and under a pressure between about 1,1 and 3 atmospheres absolute, through an aqueous catalyst solution of cuprous halide, cupric halide and an alkali metal or alkaline earth metal halide in hydrohalic acid, the ratio of monovalent copper to bivalent copper in the catalyst solution being maintained at about 3:1 to about 23:1 by oxidation with oxygen while adding hydrohalic acid or with free halogen, and the catalyst solution containing copper in a total concentration of between about 2,0 mols and about 4 mols per litre and hydrogen halide in a concentration of about 0,1 to 3,0 moles per litre of solution, a catalyst solution saturated with hydrogen halide being used when the ratio of monovalent copper to bivalent copper is smaller than about 9:1. The alkali metal or alkaline earth metal halide is preferably lithium or calcium halide and is advantageously added in a concentration equal to or higher than the total concentration of copper salts. An apparatus for continuously carrying out the process comprises a reduction chamber in which the acetylene is halogenated and an oxidation chamber in which the catalyst is regenerated to maintain the desired cuprous/cupric ratio, the catalyst solution being circulated. The product is condensed from the acetylene leaving the apparatus and the acetylene is replenished and recycled. Examples describe the preparation of trans 1,2-dichloroethylene and trans 1,2-dibromoethylene from acetylene and of trans 1,2-dichlorobutadiene from monovinylacetylene.ALSO:A catalyst for the trans-addition of halogens to acetylenes comprises an aqueous solution of cuprous halide, cupric halide and an alkali metal or alkaline earth metal halide in hydrochloric acid, the molar ratio of monovalent copper to bivalent copper being about 3:1 to about 23:1, the total copper concentration p being between about 2 and about 4 mols per litre and the hydrogen halide concentration being about 0.1 to about 3.0 mols per litre. The alkali metal or alkaline earth metal halide is preferably lithium or calcium halide and is preferably added in a concentration equal to or greater than the total concentration of copper salts. Specified compositions comprise: cuprous, cupric, hydrogen and calcium chlorides; cuprous, cupric, hydrogen and lithium chlorides; and cuprous, cupric, hydrogen and calcium bromides.